Improvement in electric speaking-telephones



PHELPS. Electric Speaking Telephones. No. 214,840. Patent-edApril-29,1879.

N. PETERS. PHOTO UTHOGRAPHEE WASHINGTON. [IV C.

W g? a,

UNITED STATES PATENT OEEIoE.

, GEORGE M. PHELPs, or BROOKLYN, NEW YORK.

IMPROVEMENT IN ELECTRIC SPEAKING-TELEPHONES.

Specification forming part of Letters Patent No. 214,840, dated April29, 1879; application filed December 6, 1878.

To all whom it may concern:

Be it known that I, GEORGE M. PHELPs of Brooklyn, in the county of Kingsand State a local battery is thrown into waves or undulations by theaction of sonorous atmospheric vibrations upon a variable resistanceinserted in said circuit.

My improvements consist, first, in providing means whereby theadjustment can be efi'ected without interrupting the continuity of thecircuit; second, in so arranging the apparatus that the vibrations ofthe diaphragm are transmitted to the variable resistance by means of. aconical or hemispherical contact-point, which will interfere butslightly with the free vibration of the diaphragm; and, third, inattaching the transmitter to its support by means of a movable jointedarm, whereby greater convenience in operating it is secured.

In the accompanying drawings, Figure 1 is a side elevation of atelephonic transmitter embodying my improvements. Fig. 2 is a verticalsection of a portion of the same, showing the construction andarrangement of the transmitting devices. Fig. 3 is a detached sectionalview of the transmitting devices. Fig. 4 is a front view of theapparatus with the mouthpiece and diaphragm removed. Figs. 5 and 6 aredetached views showing certain details of the apparatus.

The transmitting apparatus is inclosed in a cup-shaped metallic case, A,Figs. 1, 2, and 4, over the mouth of which is placed a circular plate ordisk, D, of metal, forming a diaphragm. This is secured in its positionby means of the cover B, which is placed over it, and made fast to thecase A by means of screws or otherwise. The cover B is annular in formand has a trumpet-shaped mouth-piece, G, screwed into the circularopening in its center. The transmitting apparatus proper is mounted upona metallic screw, E, Figs. 2 and 3, which is fitted into a hole boredthrough the back of the case A at its center, and closed by an outerscrew-cap, V. The screw E has a flat circular head, 0, surrounded by aflange, 0, (best seen in Fig. 3,) and upon it is fitted an annular ring,M, composed of vulcanite orother insulating material, to the face ofwhich a flat metallic ring, N, of the same or a little greater diameteris secured by screws n. (See Fig. 2.) The inner edge of theinsulating-ring M is made to project considerably-beyond the head of thescrew e, upon which it is fixed so as to form a shallow cylindrical cuphaving a metallic bottom and sides of insulating material, for thereception of a carbon button, G, a face view of which is shown in Fig.5, and a sectional view in Figs. 2 and 3. This carbon button ispreferably composed of compressed lamp-black, although other'forms ofcarbon,

and even certain metallic compositions, may

be substituted therefor with very fair results. The button G is placedloosely between two thin plates, F and H, of platinum or other infusiblemetal. The plate Fis permanently secured to the head 0 of the screw E,while the plate H is cemented to a circular plate of glass, I. The plateH has a projection, h, Figs. 2, 4, and 6, through which it is secured toand electrically connected with the metallic ring N by means of thescrew n. Upon the glass plate I, which serves both to support andinsulate it, is cemented a hemispherical or conical projection, K, theapex of which rests against the center of the diaphragm D, as best seenin Figs. 3 and 6.

The advantage of this peculiar form is, that the motion of the diaphragmD is thereby communicated from the exact center of its vibration withthe least possible interference with its freedom of movement.

The electrical connections of the apparatus are arranged as follows: Onepole of the battery is connected with the body of the case A. Theelectrical current passes thence through the screw E and platinum plateF to the carbon button G, and through the button Gr and platinum plate Hto the ring N. From the ring N (which is insulated from the case A bythe vulcanite ring M) the current passes to the contact-springs O 0,Fig. 6, which press against opposite points on the periphery of the saidring, these springs being likewise insulated from the case A by avulcanite support, P, and thence, bythe insulated wire 19, to a metallicstud or binding-screw mounted upon the insulatin g-support R. From thisaninsulated wire, Fig. 1, leads to the other pole of the battery. Inthis circuit any suitable receiving or repeatingtelephonicinstrumentmaybe placed,which will respond to the action of the transmitter. Theresistance of this circuit is controlled by the varying pressure of thediaphragm D upon the carbon button G, through the medium ofthehemispherical or conical projection K, the glassplate I, and theplatinum plate H. Thus, when articulate words are spoken or sounds areuttered in the vicinity of the mouth-piece O, the plate or diaphragm Dis thrown into vi bration in a manner well understood, and, ashereinbefore explained, those vibrations are made to control thestrength of the current by varying the resistance of the carbon buttonG.

By mounting the working parts of the transmitter upon the screw E, thenormal pressure of the diaphragm D against the carbon button G may beconveniently and accurately adjusted by simply removing the cap V andturning the screw E and its attachments from the back with an ordinaryscrew-driver. This operation does not interfere in any way with theelectrical connections, which are made by-the pressure of the springs O0 against any portion of the edge of the ring N.

For convenience of manipulation the case A,

containing the transmitting apparatus, is jointed at a to one end ofametallic arm, S, of suitable length, the other end of which is jointedinlike manner to a stationary support, T, which may, in turn, be securedto any convenient structure, W, such as a wall or window-casin g. Thisarrangement permits of the convenient use of the apparatus by persons ofvarying heights, as the flexure at the joints a and 8 permits themouth-piece (l to be placed in any position required without interferingin the least with the operation of the instrument.

I claim as my invention- 1. In a telephonic transmitter, a carbon buttonor disk, or its equivalent, and a plate of platinum or other metal heldin contact therewith by pressure, in combination with a metallic ringand one or more contact-springs, the whole being so arrangedas to admitof the adjustment of the normal pressure without interrupting theelectric circuit, substantially as specified.

2. In a telephonic transmitter, a carbon button or disk, or itsequivalent, and a plate of platinum or other metal held in contacttherewith by pressure, in combination with a hemispherical or conicalprojection, the apex of which rests against the center of the vibratingplate or diaphragm, so as to receive motion therefrom, substantially asspecified.

3. A telephonic transmitter attached to its support by means of amovable jointed arm, substantially as and for the purpose specified.

In witness whereof I have hereunto set my hand this 5th day of December,A; D.- 1878.

GEO. M. PHELPS.-

Witnesses:

WM. R. ROBERTS, WM. ARNOUX.

